1. Field of the Invention
The present invention relates to respiration devices, and, more particularly, to a simplified rebreathing device for ambulatory use which employs a carbon dioxide trap where exhaled air and fresh air are mixed to provide stimulation of respiration, greatly increased alveolar minute ventilation, and the equivalent of instant high altitude acclimatization.
2. Definitions
The following definitions are provided to enhance understanding of the concepts relating to the physiology of respiration:
Acapnia: A marked diminution in the amount of carbon dioxide (CO.sub.2) in the blood.
Apnea: Cessation of respiration. True apnea is the absence of respiratory movements owing to acapnia and the consequent lack of stimulus by CO.sub.2 to the respiratory center.
Alveolar Air: Air in the depths of the lungs which is more or less in contact with the respiratory epithelium, and can thus carry out gaseous exchanges with the blood.
Anoxia: no oxygen (O2).
Anoxic Hypoxia. Low partial pressure of O2 in the arterial blood due to interference with the oxygenation of the blood in the lungs, such as may result from a pulmonary abnormality or from a low tension O2 in the atmosphere.
Cheyne-Stokes Respiration: A type of breathing in which the respirations gradually increase in depth up to a certain point and then decrease; finally all respiration ceases for half a minute or so and then begins again as before.
Dead Space: The part of the respiratory tract possessing relatively thick walls, that is, from the nostrils to the terminal bronchioles, between which no gaseous blood interchange can take place.
Eucapnia or Eucapnic: The presence of CO.sub.2 in normal amount in the blood.
Dyspnea: Shortness of breath.
Hypercapnia: The presence of CO2 in excess in the blood.
Hyperpnea or Hyperventilation: A condition in which the respiration is deeper and more rapid than normal.
Hypocapnia: A diminution in the amount of CO.sub.2 in the blood.
Hypoxia: Low oxygen (O2),
Isocapnia: a state in which arterial CO2 remains constant.
Minute Ventilation: The tidal volume multiplied by the number of respirations per minute. For example, if a person inhales and exhales 12 times in one minute and his/her tidal volume is 0.5 liter, the minute ventilation is 6 liters per minute.
Partial Pressure: The pressure exerted by any one gas in a mixture of gases, equal to the pressure times the fraction of the total amount of gas it represents.
PCO.sub.2 : Abbreviation for partial pressure of carbon dioxide.
PO.sub.2 : Abbreviation for partial pressure of oxygen.
Q: Symbol for perfusion, the amount of blood perfusing the lungs. This amount equals the cardiac output (L/minute).
Tidal Volume: The amount of air that enters and leaves the lungs with each cycle of respiration. For example if a person inhales about 0.5 liters and exhales about 0.5 liters, the tidal volume is 0.5 liter.
V: Symbol for ventilation (L/minute).
V/Q: The ratio between ventilation and perfusion.
Vital Capacity: The greatest amount of air that can be expired after a maximal inspiratory effort.